Field
The present disclosure pertains to the use of physically unclonable functions (PUFs) to uniquely identify a memory device or device into which such memory device is integrated.
Background
Physical Unclonable functions (PUFs) provide a mechanism to uniquely identify a hardware device based on intrinsic variations of physical components. When multiple chips are manufactured, the complex semiconductor manufacturing process introduces slight variations that are beyond the control of the designer. For instance, even if two chips are manufactured from the same silicon wafer, electrical paths designed to be the same will probably differ in width by a few nanometers; microscopic differences in the surface of the silicon will induce almost trivial variations in the curvature of lines. As these unique characteristics are uncontrollable and inherent to the physical device, quantifying them can produce an intrinsic identifier. Several different types of PUFs have been proposed based on exploration and analysis of silicon variations in circuit delays, such as ring oscillator based PUFs, arbiter PUFs, and path delay analysis based PUFs.
One PUF makes use of the uninitialized power-up state of a static random access memory (SRAM) to generate an identifying “fingerprint”. However, the SRAM PUFs are susceptible to cloning attacks.
Consequently, there is a need to improve the security of current SRAM PUF designs to resist cloning attacks and invasive attacks in general.